This is a poem about the plight of captivity (and oppression) expressed as an emotional reality. The poem uses the metaphor of a physical cage as its principal vehicle to examine the nature of captivity as specific and negative way of relating to the world.
Contrasting freedom and captivity, the poem draws a comparison between a free bird that is able to not only fly freely in the sky but also to think freely.
This specific element of its freedom allows the bird to be audacious as it
[...] dares to claim the sky.
A caged bird is presented in stark relief against this emotional, imaginative and physical freedom. In a refrain repeated twice in the poem the caged bird is described with the phrase,
his wings are clipped and his feet are tiedso he opens his throat to sing.
The caged bird singswith a fearful trillof things unknownbut longed for stilland his tune is heardon the distant hillfor the caged birdsings of freedom.
his bars of rage
But a caged bird stands on the grave of dreamshis shadow shouts on a nightmare scream
The song ultimately becomes a statement of yearning that stems from loss. What has been lost is not easily stated because it is, in large part, a way of relating to the world. Yet in phrases like "grave of dreams" the poem suggests that what has been lost can be described as a power to hope, dream or believe in a positive future. A positive, assertive or affirmative relationship with the world has been taken from the caged bird.
it mean about freedom